In the twentieth century

Although the use of simple diluents and adulterants almost certainly predates recorded history, the use of fillers to modify the properties of a composition can be traced as far back as eady Roman times, when artisans used ground marble in lime plaster, frescoes, and po22olanic mortar. The use of fillers in paper and paper coatings made its appearance in the mid-nineteenth century. Functional fillers, which introduce new properties into a composition rather than modify pre-existing properties, were commercially developed eady in the twentieth century when Goodrich added carbon black to mbber and Baekeland formulated phenol— formaldehyde plastics with wood dour. 

Fibers (see Fibers, survey) used in textile production can have a wide variety of origins plants, ie, ceUulosic fibers (see Fibers, cellulose esters) animals, ie, protein fibers (see Wool) and, in the twentieth century, synthetic polymers. Depending on the part of the plant, the ceUulosic fibers can be classified as seed fibers, eg, cotton (qv), kapok bast fibers, eg, linen from flax, hemp, jute and leaf fibers, eg, agave. Protein fibers include wool and hair fibers from a large variety of mammals, eg, sheep, goats, camels, rabbits, etc, and the cocoon material of insect larvae (sUk). Real sUk is derived from the cocoon of the silkworm, Bombjx mori and for a long time was only produced in China, from which it was traded widely as a highly valuable material. 

Aryl Phosphates. Aryl phosphates were introduced into commercial use early in the twentieth century for flammable plastics such as cellulose nitrate and later for cellulose acetate. CeUulosics are a significant area of use but are exceeded now by plastici2ed vinyls (93—95). Principal appHcations are in wire and cable insulation, coimectors, automotive interiors, vinyl moisture barriers, plastic greenhouses (Japan), furniture upholstery, conveyer belts (especially in mining), and vinyl foams. 

Early in the twentieth century, the first attempts to manufacture formamide directiy from ammonia and carbon monoxide under high temperature and pressure encountered difficult technical problems and low yields (23). Only the introduction of alkaU alkoxides in alcohoHc solution, ie, the presence of alcoholate as a catalyst, led to the development of satisfactory large-scale formamide processes (24). 

The development of the principles of nucleation and growth eady in the twentieth century (2) ultimately led to the discovery that certain nucleating agents can induce a glass to crystallize with a fine-grained, highly uniform microstmcture that offers unique physical properties (3). The first commercial glass-ceramic products were missile nose cones and cookware. 

Use of lead ia modem iadusttial society results from its unique physical and chemical properties. By the middle of the nineteenth century, world production of lead had risen to 1 x 10 metric tons per year, passed 1 x 10 t /yr early in the twentieth century, and reached 1.5 x 10 t /yr by midcentury. Lead production is expected to reach 5.6 x 10 t/yr by the year 2000. 

Leather (qv) has been employed for many uses since ancient time on account of the convertibiUty of an easily decomposed substance into one which resists putrefaction. Leather is stUl an important material with its unique stmcture it is so dense in texture that it resists wind and water while retaining breathabihty and flexibiUty, which makes the resulting goods comfortable. Early attempts to imitate leather included appHcation of oil, mbber, or soluble cotton onto paper or fabrics. However, very Htde progress had been made until the era of synthetic resins began in the twentieth century. 

Galen, a physician whose views outUved him by about a thousand years, died about 200 AD. He beUeved that mercurials were toxic, and did not use any mercury compound therapeutically. However, as a result of Arabian influence, the therapeutic uses of mercury were slowly recognized by Western Europe. In the thirteenth century mercury ointments were prescribed for treating chronic diseases of the skin. Mercury and its compounds, such as mercurous chloride, mercuric oxide, mercuric chloride, and mercuric sulfide, were used widely from the fifteenth to the nineteenth centuries, and to some extent in the twentieth century. During the first half of the twentieth century, the primary therapeutic uses of mercury included bactericidal preparations, such as mercuric chloride, mercuric oxycyanide, and mercuric oxide and diuretics, such as aryl HgX (Novasural) and mercurated ahyl derivatives (14). 

For well over 100 years after its discovery and initial preparation, oxygen was made either chemically or by the electrolysis of water. Early in the twentieth century, Linde and Claude introduced processes for the Hquefaction and distillation of air that have since grown into a mature and highly competitive industry. In 1991, over 13.4 X 10 (4.7 x 10 ft ) of oxygen was produced in the United States. About 70 X 10 (24.7 x 10 ft ) was... 

U.S. Laws and Regulations Related to Drug Product Development and Manufacture. Until early in the twentieth century, dmg products were made and sold in the United States having virtually no imposed control. QuaUty was generally poor. Many products were patent medicines of dubious value. Some were harmful and addicting. 

Because of the simplicity and reUabiUty of the Rankine cycle, faciUties employing this method have dominated the power industry in the twentieth century and typically play an important role in most modem combined-cycle faciUties. Water is the working fluid of choice in nearly all Rankine cycle power plants because water is nontoxic, abundant, and low cost. 

Power plants based on the Rankine thermodynamic cycle have served the majority of the world s electric power generation needs in the twentieth century. The most common heat sources employed by Rankine cycle power plants are either fossil fuel-fired or nuclear steam generators. The former are the most widely used. 

Another representation of the stabiUty relations of the siUca minerals is shown in Figure 4. This diagram, developed in the classical studies early in the twentieth century (51), illustrates the relationship of vapor pressure to temperature. It is assumed that vapor pressure increases with temperature and that the form having the lowest vapor pressure is the most stable. The actual values of the vapor pressures are largely unknown. Therefore, the ordinate must be considered only as an indication of relative stabiUties. This diagram does not show all the various forms of tridymite that have been identified. 

The commercial production of silicon in the form of binary and ternary alloys began early in the twentieth century with the development of electric-arc and blast furnaces and the subsequent rise in iron (qv) and steel (qv) production (1). The most important and most widely used method for making silicon and silicon alloys is by the reduction of oxides or silicates using carbon (qv) in an electric arc furnace. Primary uses of silicon having a purity of greater than 98% ate in the chemical, aluminum, and electronics markets (for higher purity silicon, see Silicon AND SILICON ALLOYS, PURE SILICON). 

Medicinal Preparations. Silver nitrate is used in medicine in the form of a stick, usually containing 1—3% silver chloride, or in solutions of varying concentrations. Uses of silver in medicine as of the 1990s are much reduced from earlier in the twentieth century because of the availabiHty of a... 

Fibers have been used by humans for thousands of years, but only in the twentieth century has there been such an explosion in fiber types available to the textile manufacturer. The advent of synthetic fibers possessing improved resiliency and dimensional stability has placed natural fibers, particularly cotton (qv), at an ostensible disadvantage. Before synthetics, various means to control the shrinkage, dimensional stability, and smooth-dry performance of cotton had been investigated, but the appearance of synthetics such as polyester has placed a greater sense of urgency on cotton interests to focus on the perceived deficiencies of natural fibers. 

Early in the twentieth century physicists established that molecules are composed of positively charged nuclei and negatively charged electrons. Given their tiny size and nonclassical behavior, exemplified by the Heisenberg uncertainty principle, it is remarkable (at least to me) that Eq. (1) can be considered exact as a description of the electrostatic forces acting between the atomic nuclei and electrons making up molecules and molecular systems. Eor those readers who are skeptical, and perhaps you should be skeptical of such a claim, I recommend the very readable introduction to Jackson s electrodynamics book [1]. 

The invention of air conditioning is actually a progression of the applied ideas of many individuals starting in the early nineteenth century and dramatically accelerating in the twentieth century. Most air conditioning developments occurred in the twentieth century. 

Lightolier. (1994). Journey Lightolier and Lighting in the Twentieth Century. New York Lightolier. 

The relatively soluble calcium compounds formed this way [CaS04. Ca(N03)2] are gradually washed away (Figure B). This process is responsible for the deterioration of the Greek ruins on the Acropolis in Athens. These structures suffered more damage in the twentieth century than in the preceding 2000 years. 

In the twentieth century, Jell-O found its way into salads, song ( A Fine Romance from the Rogers and Astaire musical Swing Time in 1936— You take romance, I ll take Jell-O ), academic conferences (the Smithsonian Institution s 1991 symposium on Jell-O included a session on Jell-O wrestling) and outer space. Dr. Shannon W. Lucid, an American mother of three, served Jell-O to Russian astronauts on the Mir Station in 1996 on Easter Sunday. 

Wentzel, G., Quantum Theory of Fields, in Theoretical Physics in the Twentieth Century, A Memorial Volume to W. Pauli, M. Fierz, and V. F. Weisskopf, ed., Interscience Publishers, Inc., New York, 1960. 

With the advent of atomic energy in the twentieth century, the Law of Conservation of Energy needed to be modified to include mass as a form of stored energy, with the equivalence given by the equation E = me2. 

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